In the catalogue of the collection of instruments of the Institute for the History of Arabic and Islamic Sciences, an apparatus is mentioned for the observation of the reflection of light. The idea of the apparatus is brought forward by Ibn al-Haytham, the eleventh-century scholar who has been praised for his breakthroughs in optics as he was the first scientist who made big steps in this field since Ptolomy. The apparatus gives experimental proof of the law of reflection. In his tract on optics, Ibn al-Haytham provided his mathematical proof. The apparatus covers the basic configuration of the experiment. In his mathematics, he dealt with all kinds of situations, as I mentioned in 2019. His predecessors limited themselves to the easy case where the eye and the source of light are at the same distance of the center of a cylindrical mirror. Ibn al-Haytham solved the far more difficult general case where the light and eye are not at the same distance of the center, using a mix of practical experiments, conic sections, and rigorous mathematical proofs.
The Istanbul Museum of the History of Science and Technology in Islam exhibits a precious new-build apparatus. Experiments with this replica were successful. One clearly sees the rays of light and the reflection of these rays in all kind of mirrors (flat, conical, spherical, etc..).
My paper discusses the mathematical and experimental works of Ibn al-Haytam and presents a lesson series. My aim is to develop a hands-on classroom lesson series using a low-cost 3D-printed apparatus to bring the optics of Ibn al-Haytham alive. The story is also about the advanced use of mathematics by Ibn al-Haytham, which goes far beyond high school mathematics. In my lecture, I would like to address the important role of the optics of Ibn al-Haytham and present an outline of that lesson series. Afterward, in a workshop, the apparatus and the lesson series can be demonstrated.
Design of our prototype
Our design is ready, waiting for a first prototype.
Illustrations are from the catalogue of the collection of instruments of the Institute for the History of Arabic and Islamic Sciences.
Our experiment proves that this setup of the apparatus does work. Next step is to develop a low cost reliable 3D printed version of this apparatus that is suitable for classroom demonstrations. Light source will be a cellphone! So every student can do this experiment with his own device!
In his treatise On the Shape of the Eclipse, Ibn al-Haytham investigated the image of a crescent solar eclipse through a pinhole of a camera obscura. Since 1940, a small group of authors elaborated on Ibn al-Haytham's texts, to name a few: Nazif, Sabra, Smith and Raynaud. Since the fifteenth century, Western scholars tried to master the topic but it took until the seventeenth century before their were right solutions.
Nazif presented an interesting drawing with multiple cones. In order to emphasize these cones, color is added in the right picture.
In his critical edition of Ibn al-Haytham's Eclipse, Raynaud presented drawings from a selected number of manuscripts of Ibn al-Haytham.
All above images show three upside down crescents, while Gemma Frisius only mentions one crescent in his book in 1545.
One century later, in 1671, père Chérubin d' Orléans presented a drawing with three cones`, but for some reason, the straight lines are broken in the aperture. According to the text there is no lense, but the broken lines do suggest lenses.
Mihas published his article A Historical Approach to the Teaching of the Linear Propagation of Light, Shadows and Pinhole Cameras in 2005. He presented the same three cones and a computer simulation to predict the final shape: the image of a crescent looks like a peach!
Raynaud did computer simualations too with the same result: the image of the crescent looks more like a peach than a croisssant. My simulation shows similar results. The top rows show the crescent, the bottom row the image at 2500 mm distance and aperture diameter 11 mm.
The image of the eclipse becomes much better with a smaller aperture of radius 1 or 2 mm.